1. Field of the Invention
This invention pertains generally to the field of display systems such as, but not limited to, aircraft display systems.
2. Description of the Related Art
The United States Federal Aviation Administration (“FAA”) has published a Technical Standard Order (“TSO”) identified as TSO-151c in which minimum performance standards of a Terrain Awareness and Warning System (“TAWS”) are specified. TSO-151c defines standards of alert conditions corresponding to forward looking terrain avoidance (“FLTA”) functions, a premature descent alert (“PDA”) function, and a plurality of ground proximity functions. For each of these functions, visual and aural alerts are required if specific conditions stated in the TSO-151c are met. For visual alerts, amber and red text messages are required for caution and warning alerts, respectively. Although text alerts are specified in TSO-151c, there is no requirement to present other forms of visual presentation(s) or to provide useful, graphical general terrain information.
With respect to a flight plan, an image of an aerial pathway that appears on an aircraft display unit is useful and informative to the pilot of an aircraft; for one reason, it provides guidance information within the scene outside the aircraft, thereby enhancing a pilot's situational awareness. One image of an aerial pathway is commonly referred to as a highway-in-the-sky (“HITS”), the generation and employment of which are known to those skilled in the art. An aerial pathway comprised of an abbreviated pathway has been disclosed by Chiew et al in U.S. Pat. No. 7,965,202 (“the Chiew reference”), where the abbreviated pathway comprised of a series of connected waypoints was shown. Although the HITS pathway and abbreviated pathway disclosed in the Chiew reference provide useful guidance information, it is difficult to discern the ground track underneath the pathway. Moreover, it is difficult to visually discern approaching terrain clearances; that is, the distances between the altitude of the aircraft and the terrain over which it is expected to fly.